Categorization of Select Cockpit Performance Evaluation Techniques.

INTRODUCTION: The modern aircraft cockpit has evolved into a complex system of systems. Numerous performance evaluation metrics and techniques exist that can measure the effectiveness of cockpit components in terms of how they influence the human operator's ability to perform tasks relevant to mission success. As no prior review of these metrics has been found in the literature, this effort attempts to do so, albeit without applying the metrics to a novel cockpit evaluation.METHODS: These metrics and techniques are discussed and presented in five defined categories as they relate to evaluating cockpit subsystems: ergonomics and anthropometrics; human-computer interaction; data management and presentation; crew resource management and operations; and ingress and egress.DISCUSSION: While this effort is significant and novel, it is not necessarily comprehensive. In conclusion, it is noted that no single holistic quantitative metric to evaluate cockpit design and performance yet exists. Utilizing some of the preexisting metrics presented to develop such a metric would be beneficial in efforts to evaluate aircraft cockpit designs and performance, as well as aiding future cockpit designs.Brighton EM, Klaus DM. Categorization of select cockpit performance evaluation techniques. Aerosp Med Hum Perform. 2023; 94(9):696-704.

Simulated Micro-, Lunar, and Martian Gravities on Earth-Effects on Escherichia coli Growth, Phenotype, and Sensitivity to Antibiotics.

Bacterial behavior has been studied under microgravity conditions, but very little is known about it under lunar and Martian gravitational regimes. An Earth-based approach was designed and implemented using inclined clinostats and an in-house-developed code to determine the optimal clinorotation angular speed for bacterial liquid cultures of 5 RPM. With this setup, growth dynamics, phenotypic changes, and sensitivity to antibiotics (minimum inhibitory concentration (MIC) of two different classes of antibiotics) for three Escherichia coli strains (including uropathogenic) were examined under simulated micro-, lunar, and Martian gravities. The results included increased growth under simulated micro- and lunar gravities for some strains, and higher concentrations of antibiotics needed under simulated lunar gravity with respect to simulated micro- and Martian gravities. Clinostat-produced results can be considered suggestive but not determinative of what might be expected in altered gravity, as there is still a need to systematically verify these simulation devices' ability to accurately replicate phenomena observed in space. Nevertheless, this approach serves as a baseline to start interrogating key cellular and molecular aspects relevant to microbial processes on the lunar and Martian surfaces.

Side-by-Side Comparison of Human Perception and Performance Using Augmented, Hybrid, and Virtual Reality.

Alternative reality (XR) technologies, including physical, augmented, hybrid, and virtual reality, offer ways for engineered spaces to be evaluated. Traditionally, practitioners (such as those designing spacecraft habitats) have relied on physical mockups to perform such design evaluations, but digital XR technologies present several streamlining advantages over their physical counterparts. These digital environments vary in their level of virtuality, and consequently have different effects on human perception and performance, with respect to a completely physical mockup environment. To date, very little has been done to characterize and quantify such differences in human perception and performance across XR environments of equal fidelity for the same end application. Here, we show that perception and performance in the virtual reality environment most closely mirror those in the physical reality environment, as measured through volumetric assessment and functional task experiments. These experiments required subjects to judge the dimensions of 3D objects and perform operational tasks presented via checklists. Our results highlight the potential for virtual reality systems to accelerate the iterative design of engineered spaces relative to the use of physical mockups, while preserving the human perception and performance characteristics of a completely physical environment. These findings also elucidate specific advantages and disadvantages to specific digital XR technologies with respect to one another and the physical reality baseline. Practitioners may inform their selection of an XR modality for their specific end application based on this comparative analysis, as it contextualizes the niche for each technology in the realm of iterative design for engineered spaces.

Design of a spaceflight biofilm experiment.

Biofilm growth has been observed in Soviet/Russian (Salyuts and Mir), American (Skylab), and International (ISS) Space Stations, sometimes jeopardizing key equipment like spacesuits, water recycling units, radiators, and navigation windows. Biofilm formation also increases the risk of human illnesses and therefore needs to be well understood to enable safe, long-duration, human space missions. Here, the design of a NASA-supported biofilm in space project is reported. This new project aims to characterize biofilm inside the International Space Station in a controlled fashion, assessing changes in mass, thickness, and morphology. The space-based experiment also aims at elucidating the biomechanical and transcriptomic mechanisms involved in the formation of a "column-and-canopy" biofilm architecture that has previously been observed in space. To search for potential solutions, different materials and surface topologies will be used as the substrata for microbial growth. The adhesion of bacteria to surfaces and therefore the initial biofilm formation is strongly governed by topographical surface features of about the bacterial scale. Thus, using Direct Laser-Interference Patterning, some material coupons will have surface patterns with periodicities equal, above or below the size of bacteria. Additionally, a novel lubricant-impregnated surface will be assessed for potential Earth and spaceflight anti-biofilm applications. This paper describes the current experiment design including microbial strains and substrata materials and nanotopographies being considered, constraints and limitations that arise from performing experiments in space, and the next steps needed to mature the design to be spaceflight-ready.

Spaceflight Modifies Escherichia coli Gene Expression in Response to Antibiotic Exposure and Reveals Role of Oxidative Stress Response.

Bacteria grown in space experiments under microgravity conditions have been found to undergo unique physiological responses, ranging from modified cell morphology and growth dynamics to a putative increased tolerance to antibiotics. A common theory for this behavior is the loss of gravity-driven convection processes in the orbital environment, resulting in both reduction of extracellular nutrient availability and the accumulation of bacterial byproducts near the cell. To further characterize the responses, this study investigated the transcriptomic response of Escherichia coli to both microgravity and antibiotic concentration. E. coli was grown aboard International Space Station in the presence of increasing concentrations of the antibiotic gentamicin with identical ground controls conducted on Earth. Here we show that within 49 h of being cultured, E. coli adapted to grow at higher antibiotic concentrations in space compared to Earth, and demonstrated consistent changes in expression of 63 genes in response to an increase in drug concentration in both environments, including specific responses related to oxidative stress and starvation response. Additionally, we find 50 stress-response genes upregulated in response to the microgravity when compared directly to the equivalent concentration in the ground control. We conclude that the increased antibiotic tolerance in microgravity may be attributed not only to diminished transport processes, but also to a resultant antibiotic cross-resistance response conferred by an overlapping effect of stress response genes. Our data suggest that direct stresses of nutrient starvation and acid-shock conveyed by the microgravity environment can incidentally upregulate stress response pathways related to antibiotic stress and in doing so contribute to the increased antibiotic stress tolerance observed for bacteria in space experiments. These results provide insights into the ability of bacteria to adapt under extreme stress conditions and potential strategies to prevent antimicrobial-resistance in space and on Earth.

Spacecraft cabin environment effects on the growth and behavior of Chlorella vulgaris for life support applications.

An Environmental Control and Life Support System (ECLSS) is necessary for humans to survive in the hostile environment of space. As future missions move beyond Earth orbit for extended durations, reclaiming human metabolic waste streams for recycled use becomes increasingly important. Historically, these functions have been accomplished using a variety of physical and chemical processes with limited recycling capabilities. In contrast, biological systems can also be incorporated into a spacecraft to essentially mimic the balance of photosynthesis and respiration that occurs in Earth's ecosystem, along with increasing the reuse of biomass throughout the food chain. In particular, algal photobioreactors that use Chlorella vulgaris have been identified as potential multifunctional components for use as part of such a bioregenerative life support system (BLSS). However, a connection between the biological research examining C. vulgaris behavior and the engineered spacecraft cabin environmental conditions has not yet been thoroughly established. This review article characterizes the ranges of prior and expected cabin parameters (e.g. temperature, lighting, carbon dioxide, pH, oxygen, pressure, growth media, contamination, gravity, and radiation) and reviews algal metabolic response (e.g. growth rate, composition, carbon dioxide fixation rates, and oxygen evolution rates) to changes in those parameters that have been reported in prior space research and from related Earth-based experimental observations. Based on our findings, it appears that C. vulgaris offers many promising advantages for use in a BLSS. Typical atmospheric conditions found in spacecraft such as elevated carbon dioxide levels are, in fact, beneficial for algal cultivation. Other spacecraft cabin parameters, however, introduce unique environmental factors, such as reduced total pressure with elevated oxygen concentration, increased radiation, and altered gravity, whose effects on the biological responses of C. vulgaris are not yet well understood. A summary of optimum growth parameter ranges for C. vulgaris is presented in this article as a guideline for designing and integrating an algal photobioreactor into a spacecraft life support system. Additional research challenges for evaluating as of yet uncharacterized parameters are also identified in this article that have the potential for improving spaceflight applications as well as terrestrial aquatic algal cultivation systems.

Phenotypic Changes Exhibited by E. coli Cultured in Space.

Bacteria will accompany humans in our exploration of space, making it of importance to study their adaptation to the microgravity environment. To investigate potential phenotypic changes for bacteria grown in space, Escherichia coli was cultured onboard the International Space Station with matched controls on Earth. Samples were challenged with different concentrations of gentamicin sulfate to study the role of drug concentration on the dependent variables in the space environment. Analyses included assessments of final cell count, cell size, cell envelope thickness, cell ultrastructure, and culture morphology. A 13-fold increase in final cell count was observed in space with respect to the ground controls and the space flight cells were able to grow in the presence of normally inhibitory levels of gentamicin sulfate. Contrast light microscopy and focused ion beam/scanning electron microscopy showed that, on average, cells in space were 37% of the volume of their matched controls, which may alter the rate of molecule-cell interactions in a diffusion-limited mass transport regime as is expected to occur in microgravity. TEM imagery showed an increase in cell envelope thickness of between 25 and 43% in space with respect to the Earth control group. Outer membrane vesicles were observed on the spaceflight samples, but not on the Earth cultures. While E. coli suspension cultures on Earth were homogenously distributed throughout the liquid medium, in space they tended to form a cluster, leaving the surrounding medium visibly clear of cells. This cell aggregation behavior may be associated with enhanced biofilm formation observed in other spaceflight experiments.

A Molecular Genetic Basis Explaining Altered Bacterial Behavior in Space.

Bacteria behave differently in space, as indicated by reports of reduced lag phase, higher final cell counts, enhanced biofilm formation, increased virulence, and reduced susceptibility to antibiotics. These phenomena are theorized, at least in part, to result from reduced mass transport in the local extracellular environment, where movement of molecules consumed and excreted by the cell is limited to diffusion in the absence of gravity-dependent convection. However, to date neither empirical nor computational approaches have been able to provide sufficient evidence to confirm this explanation. Molecular genetic analysis findings, conducted as part of a recent spaceflight investigation, support the proposed model. This investigation indicated an overexpression of genes associated with starvation, the search for alternative energy sources, increased metabolism, enhanced acetate production, and other systematic responses to acidity-all of which can be associated with reduced extracellular mass transport.

Two-dimensional pattern formation using graphoepitaxy of PS-b-PMMA block copolymers for advanced FinFET device and circuit fabrication.

Directed self-assembly (DSA) of lamellar phase block-co-polymers (BCPs) can be used to form nanoscale line-space patterns. However, exploiting the potential of this process for circuit relevant patterning continues to be a major challenge. In this work, we propose a way to impart two-dimensional pattern information in graphoepitaxy-based lamellar phase DSA processes by utilizing the interactions of the BCP with the template pattern. The image formation mechanism is explained through the use of Monte Carlo simulations. Circuit patterns consisting of the active region of Si FinFET transistors, referred to as Si "fins", were fabricated to demonstrate the applicability of this technique to the formation of complex patterns. The quality of the Si fin features produced by this process was validated by demonstrating the first functional DSA-patterned FinFET devices with 29 nm-pitch fins.

Space microbiology.

The responses of microorganisms (viruses, bacterial cells, bacterial and fungal spores, and lichens) to selected factors of space (microgravity, galactic cosmic radiation, solar UV radiation, and space vacuum) were determined in space and laboratory simulation experiments. In general, microorganisms tend to thrive in the space flight environment in terms of enhanced growth parameters and a demonstrated ability to proliferate in the presence of normally inhibitory levels of antibiotics. The mechanisms responsible for the observed biological responses, however, are not yet fully understood. A hypothesized interaction of microgravity with radiation-induced DNA repair processes was experimentally refuted. The survival of microorganisms in outer space was investigated to tackle questions on the upper boundary of the biosphere and on the likelihood of interplanetary transport of microorganisms. It was found that extraterrestrial solar UV radiation was the most deleterious factor of space. Among all organisms tested, only lichens (Rhizocarpon geographicum and Xanthoria elegans) maintained full viability after 2 weeks in outer space, whereas all other test systems were inactivated by orders of magnitude. Using optical filters and spores of Bacillus subtilis as a biological UV dosimeter, it was found that the current ozone layer reduces the biological effectiveness of solar UV by 3 orders of magnitude. If shielded against solar UV, spores of B. subtilis were capable of surviving in space for up to 6 years, especially if embedded in clay or meteorite powder (artificial meteorites). The data support the likelihood of interplanetary transfer of microorganisms within meteorites, the so-called lithopanspermia hypothesis.

Antibiotic efficacy and microbial virulence during space flight.

Human space flight is a complex undertaking that entails numerous technological and biomedical challenges. Engineers and scientists endeavor, to the extent possible, to identify and mitigate the ensuing risks. The potential for an outbreak of an infectious disease in a spacecraft presents one such concern, which is compounded by several components unique to an extraterrestrial environment. Various factors associated with the space flight environment have been shown to potentially compromise the immune system of astronauts, increase microbial proliferation and microflora exchange, alter virulence and decrease antibiotic effectiveness. An acceptable resolution of the above concerns must be achieved to ensure safe and efficient space habitation. To help bring this about, scientists are employing advances in biotechnology to better characterize the relevant variables and establish appropriate solutions. Because many of these clinical concerns are also relevant in terrestrial society, this research will have reciprocal benefits back on Earth.

Preflight virtual reality training as a countermeasure for space motion sickness and disorientation.

INTRODUCTION: Research suggests that preflight training in virtual reality devices can simulate certain aspects of microgravity and may prove to be an effective countermeasure for space motion sickness (SMS) and spatial disorientation (SD). It is hypothesized that exposing subjects preflight to variable virtual orientations, similar to those encountered during spaceflight, will reduce the incidence and/or severity of SMS and SD. METHODS: Subjects were assigned to either a variable training (VT) or nonvariable training (NVT) condition to perform a simple navigation and switch activation task in a virtual space station. VT subjects performed the task starting in several different orientations, whereas NVT subjects always performed the task starting in the same orientation. On a separate day, all subjects then performed the same task in a transfer of training session starting from a novel orientation. RESULTS: When exposed to the novel test orientation, VT subjects performed the tasks more quickly (12%) and with fewer nausea symptoms (53%) than during the training session, compared with NVT subjects who performed more slowly (6%) and with more nausea symptoms (28%). Both VT and NVT conditions were effective in reducing the number of wall hits in the novel orientation (39% and 34%, respectively). DISCUSSION: These results demonstrate the effectiveness of using variable training in a virtual environment for reducing nausea and improving task performance in potentially disorienting surroundings, and suggest that such training may be developed into an effective countermeasure for SMS, SD, and associated performance decrements that occur in spaceflight.

Can genetically modified Escherichia coli with neutral buoyancy induced by gas vesicles be used as an alternative method to clinorotation for microgravity studies?

Space flight has been shown to affect various bacterial growth parameters. It is proposed that weightlessness allows the cells to remain evenly distributed, consequently altering the chemical makeup of their surrounding fluid, and hence indirectly affecting their physiological behaviour. In support of this argument, ground-based studies using clinostats to partially simulate the quiescent environment attained in microgravity have generally been successful in producing bacterial growth characteristics that mimic responses reported under actual space conditions. A novel approach for evaluating the effects of reduced cell sedimentation is presented here through use of Escherichia coli cultures genetically modified to be neutrally buoyant. Since clinorotation would not (or would only minimally) affect cell distribution of this already near-colloidal cell system, it was hypothesized that the effects on final population density would be eliminated relative to a static control. Gas-vesicle-producing E. coli cultures were grown under clinostat and static conditions and the culture densities at 60 h were compared. As a control, E. coli that do not produce gas vesicles, but were otherwise identical to the experimental strain, were also grown under clinostat and static conditions. As hypothesized, no significant difference was observed in cell populations at 60 h between the clinorotated and static gas-vesicle-producing E. coli cultures, while the cells that did not produce gas vesicles showed a mean increase in population density of 10.5 % (P = 0.001). These results further suggest that the lack of cumulative cell sedimentation is the dominant effect of space flight on non-stirred, in vitro E. coli cultures.

An ultrasonic methodology for muscle cross section measurement to support space flight.

The number one priority for any manned space mission is the health and safety of its crew. The study of the short and long term physiological effects on humans is paramount to ensuring crew health and mission success. One of the challenges associated in studying the physiological effects of space flight on humans, such as loss of bone and muscle mass, has been that of readily attaining the data needed to characterize the changes. The small sampling size of astronauts, together with the fact that most physiological data collection tends to be rather tedious, continues to hinder elucidation of the underlying mechanisms responsible for the observed changes that occur in space. Better characterization of the muscle loss experienced by astronauts requires that new technologies be implemented. To this end, we have begun to validate a 360 degree ultrasonic scanning methodology for muscle measurements and have performed empirical sampling of a limb surrogate for comparison. Ultrasonic wave propagation was simulated using 144 stations of rotated arm and calf MRI images. These simulations were intended to provide a preliminary check of the scanning methodology and data analysis before its implementation with hardware. Pulse-echo waveforms were processed for each rotation station to characterize fat, muscle, bone, and limb boundary interfaces. The percentage error between MRI reference values and calculated muscle areas, as determined from reflection points for calf and arm cross sections, was -2.179% and +2.129%, respectively. These successful simulations suggest that ultrasound pulse scanning can be used to effectively determine limb cross-sectional areas. Cross-sectional images of a limb surrogate were then used to simulate signal measurements at several rotation angles, with ultrasonic pulse-echo sampling performed experimentally at the same stations on the actual limb surrogate to corroborate the results. The objective of the surrogate sampling was to compare the signal output of the simulation tool used as a methodology validation for actual tissue signals. The disturbance patterns of the simulated and sampled waveforms were consistent. Although only discussed as a small part of the work presented, the sampling portion also helped identify important considerations such as tissue compression and transducer positioning for future work involving tissue scanning with this methodology.

Extracellular mass transport considerations for space flight research concerning suspended and adherent in vitro cell cultures.

Conducting biological research in space requires consideration be given to isolating appropriate control parameters. For in vitro cell cultures, numerous environmental factors can adversely affect data interpretation. A biological response attributed to microgravity can, in theory, be explicitly correlated to a specific lack of weight or gravity-driven motion occurring to, within or around a cell. Weight can be broken down to include the formation of hydrostatic gradients, structural load (stress) or physical deformation (strain). Gravitationally induced motion within or near individual cells in a fluid includes sedimentation (or buoyancy) of the cell and associated shear forces, displacement of cytoskeleton or organelles, and factors associated with intra- or extracellular mass transport. Finally, and of particular importance for cell culture experiments, the collective effects of gravity must be considered for the overall system consisting of the cells, their environment and the device in which they are contained. This does not, however, rule out other confounding variables such as launch acceleration, on orbit vibration, transient acceleration impulses or radiation, which can be isolated using onboard centrifuges or vibration isolation techniques. A framework is offered for characterizing specific cause-and-effect relationships for gravity-dependent responses as a function of the above parameters.

A modular suite of hardware enabling spaceflight cell culture research.

BioServe Space Technologies, a NASA Research Partnership Center (RPC), has developed and operated various middeck payloads launched on 23 shuttle missions since 1991 in support of commercial space biotechnology projects. Modular cell culture systems are contained within the Commercial Generic Bioprocessing Apparatus (CGBA) suite of flight-qualified hardware, compatible with Space Shuttle, SPACEHAB, Spacelab and International Space Station (ISS) EXPRESS Rack interfaces. As part of the CGBA family, the Isothermal Containment Module (ICM) incubator provides thermal control, data acquisition and experiment manipulation capabilities, including accelerometer launch detection for automated activation and thermal profiling for culture incubation and sample preservation. The ICM can accommodate up to 8 individually controlled temperature zones. Command and telemetry capabilities allow real-time downlink of data and video permitting remote payload operation and ground control synchronization. Individual cell culture experiments can be accommodated in a variety of devices ranging from 'microgravity test tubes' or standard 100 mm Petri dishes, to complex, fed-batch bioreactors with automated culture feeding, waste removal and multiple sample draws. Up to 3 levels of containment can be achieved for chemical fixative addition, and passive gas exchange can be provided through hydrophobic membranes. Many additional options exist for designing customized hardware depending on specific science requirements.

Microgravity materials and life sciences research applications of digital holography.

We investigate the utility of digital holographic interferometry for analyzing gravity-dependent mass transport phenomena as applicable to materials and life science research topics. Digital holography is useful for measurement of parameters that introduce phase changes in light traversing the material of interest, such as temperature or concentration variations in an aqueous environment. We have constructed, tested, and verified a compact, portable digital holographic monitor (DHM) suitable for characterization of transparent samples. It has proved useful for the study of systems such as protein crystal growth solutions and has been proposed for further application into studies involving microbial metabolism. The DHM is also sufficiently rugged for field operation in challenging environments a s may be encountered in a spacecraft or industrial setting. We discuss some system capabilities and limitations.

Investigation of space flight effects on Escherichia coli and a proposed model of underlying physical mechanisms.

Previous investigations have reported that space flight may produce a stimulating effect on microbial metabolism; however, the specific underlying mechanisms associated with the observed changes have not yet been identified. In an effort to systematically evaluate the effect of space flight on each phase of microbial growth (lag, exponential and stationary), a series of experiments was carried out using in vitro suspension cultures of Escherichia coli aboard seven US Space Shuttle missions. The results indicated that, as a result of space flight, the lag phase was shortened, the duration of exponential growth was increased, and the final cell population density was approximately doubled. A model was derived from these cumulative data in an attempt t associate gravity-dependent, extracellular transport phenomena with unique changes observed in each specific phase of growth. It is suggested that a cumulative effect of gravity may have a significant impact on suspended cells via their fluid environment, where an immediate, direct influence of gravity might otherwise be deemed negligible.